A traditional computer system has an implicit ability to communicate between its own local processors and from the local processors to its own I/O adapters and the devices attached to its I/O adapters. Traditionally, processors communicate with other processors, memory, and other devices via processor-memory buses. I/O adapters communicate via buses attached to processor-memory buses. The processors and I/O adapters on a first computer system are typically not directly accessible to other processors and I/O adapters located on a second computer system.
For reasons stated above and for other reasons presented in greater detail in the description of the preferred embodiments section of the present specification, there is a need for an improved partitioning mechanism in distributed computer systems to permit efficient direct accessibility by processors and I/O adapters on a first computer system to other processors and I/O adapters located on a second computer system.